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NORTHEASTERN IDAHO REGION

ALL HAZARD MITIGATION PLAN

REGIONAL SUMMARY

2008

Northeastern Idaho

Regional AHMP March 3, 2009

1

Table of Contents

Section 1 Introduction…………………………………………………. 3

Section 2 Hazard Analysis…………………………………………. …. 9

Section 3 Mitigation Projects………………………………………. …. 63

Attachments……………………………………………………………. 65

Ririe Dam Failure Mitigation Project

Palisades Dam Failure Mitigation Project

Dam Failure Notification Systems for the Island Park Reservoir

Mackay Dam Failure Notification System Project

Protect Power Supply for Butte and Custer Counties

Channel Distribution on the South Fork of the Snake River

Hazardous Materials Transportation Planning

Upper Snake River Basin Cloud Seeding Project

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Northeastern Idaho Region

All Hazard Mitigation Planning

Regional Summary

Section 1 Introduction

The Northeastern Idaho Region All Hazard Mitigation Plan has been developed as a regional

summary of the hazards identified in the individual county All Hazard Mitigation Plans. It is

intended to be an integrating document, with the sole purpose of identifying possible mitigation

projects that cross county jurisdictional boundaries.

Discussion

Hazard mitigation is defined as any cost-effective action(s) that has the effect of reducing,

limiting, or preventing vulnerability of people, culture, property, and the environment to

potentially damaging, harmful, or costly hazards. Hazard mitigation measures which can be used

to eliminate or minimize the risk to life, culture and property, fall into three categories:

1) Keep the hazard away from people, property, and structures.

2) Keep people, property, or structures away from the hazard.

3) Reduce the impact of the hazard on victims, i.e., insurance.

Hazard mitigation measures must be practical, cost effective, and culturally, environmentally,

and politically acceptable. Actions taken to limit the vulnerability of society to hazards must not

in themselves be more costly than the anticipated damages.

The primary focus of hazard mitigation planning must be at the point at which capital investment

and land use decisions are made, based on vulnerability. Capital investments, whether for

homes, roads, public utilities, pipelines, power plants, or public works, determine to a large

extent the nature and degree of hazard vulnerability of a community. Once a capital facility is

in place, very few opportunities will present themselves over the useful life of the facility to

correct any errors in location or construction with respect to the hazard vulnerability. It is for

this reason that zoning and other ordinances, which manage development in high vulnerability

areas, and building codes, which insure that new buildings are built to withstand the damaging

forces of the hazards, is often the most useful tool in mitigation that a jurisdiction can implement.

Since the priority to implement mitigation activities is usually very low in comparison to the

perceived threat, some important mitigation measures take time to implement. Mitigation

success can be achieved, however, if accurate information is portrayed through complete hazard

identification and impact studies, followed by effective mitigation management.

The Federal Disaster Services Agency has identified hazards to be analyzed by each jurisdiction,

completing an all hazard mitigation plan as part of the process. The hazards analyzed include the

following:

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Natural Hazards

Weather: Drought

Extreme Heat

Extreme Cold

Severe Winter Storm

Lightning

Hail

Tornado

Straight Line Wind

Flooding: Flash Flood

River Flooding

Dam Failure

Geologic: Earthquake

Landslide/Mudslide

Other: Wildfire

Biological

Pandemic/Epidemic

Bird Flu

SARs

West Nile

Technological (Manmade) Hazards

Structural Fire

Nuclear Event

Hazardous Material Event

Riot/Demonstration/Civil Disorder

Terrorism

Those hazards which pose a Regional threat as defined herein include;

Drought

Winter Storm

Flooding

Dam Failure

Earthquake

Wildfire

Nuclear

Hazardous Materials

Purpose

The purposes of this plan are:

Highlight hazards in the Region;

Promote pre- and post-disaster mitigation measures with short/long range strategies to

minimize suffering, loss of life, impact on traditional culture, and damage to property and

the environment;

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Eliminate or minimize conditions that would have an undesirable impact on the people,

culture, economy, environment, and well being of the Region at large.

Enhance the Region‟s elected officials‟, departments‟, and the public‟s awareness of the

threats to the Region‟s way of life, and of what can be done to prevent or reduce the

vulnerability and risk.

Scope

The Northeastern Idaho Regional All Hazard Mitigation Plan covers the following nine

Counties:

Lemhi

Custer

Butte

Fremont

Clark

Teton

Madison

Bonneville

Jefferson

Risk Analysis

A risk analysis was conducted for each county and quantified using the information gathered to

assess risk; information concerning the potential amount of damage a hazard event can cause

(hazard magnitude), and that pertaining to how frequently such events are likely to occur (hazard

frequency). Risk assessment methods included the use of FEMA‟s HAZUS Risk Assessment

software. Risk assessment activities also included the mapping of hazard occurrences, at-risk

structures including critical facilities, and repetitive flood loss structures, land use, and

populations.

Hazard magnitude estimates rely on data gathered from a number of sources, none of which

may be precise. Historical data, scientific projections, and inhabitants‟ subjective judgments are,

again, used for this purpose. Magnitude estimates are generally based on the severity of

potential impact on three critical vulnerabilities: human life, property, and the environment.

FEMA has, however, recognized that there are other issues tied to community support of risk

mitigation including social, cultural, and economical issues. Composite data from all sources was

utilized to assign a quantitative magnitude for each hazard for the Counties and for each local

jurisdiction, based on the criteria shown in Table 1.1.

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Magnitude of Natural Disasters

Value Reconstruction

Assistance From

Geography

(Area)

Affected

Expected Bodily

Harm

Loss Estimate

Range

Population

Sheltering

Required

Warning

Lead

Times

1 Family Parcel Little to No

Injury / No Death $1000s

No

Sheltering Months

2 City

Block or

Group of

Parcels

Multiple Injuries

with Little to No

Medical Care /

No Death

$10,000s Little

Sheltering Weeks

2 Counties

Section or

Numerous

Parcels

Major Medical

Care Required /

Minimal Death

$100,000s

Sheltering

Requiring

Neighboring

Counties

Help

Days

4 State Multiple

Sections

Major Injuries /

Requires Help

from Outside

Counties / A Few

Deaths

$1,000,000s

Long Term

Sheltering

Effort

Hours

8 Federal Counties

Wide

Massive

Casualties /

Catastrophic

$10,000,000s Relocation

Required Minutes

Table 1.1 Hazard Magnitude Criteria

A hazard‟s total magnitude is the sum of the values for each of the six categories. Thus, a hazard

event that is expected to require Reconstruction Assistance from the State government (Value =

4), affect an area consisting of Multiple Sections (Value = 4), cause Little to No Injury and No

Deaths (Value = 1), require Little Sheltering (Shelter = 2) or cause Some Economic Loss (Value

= 2), and have a Warning Lead Time of Hours (Value = 4), would be assigned a magnitude value

of 17 (4+4+1+2+2+4=17).

Frequency of occurrence for a given hazard was estimated using historical records. The value

of frequency estimates obtained in this way is subject to the existence of such records, their

availability, and their accuracy. Even with good historical records, however, projections of

future frequency may not be valid because of changing conditions. Long- and short-term climate

cycles (among other factors) affect weather events, economic conditions and technical advances

affect man-made hazards, land use and the passage of time affect geological hazards, etc. For

this reason, scientific projections, when available, were also used to modify, enhance or replace

those made from historical data. For any given location, however, historical records are often

scarce and/or unreliable, and scientific projection methods either do not exist or require data that

has not been, or cannot be gathered. Thus, a third source of frequency data was utilized in this

Planning effort; the subjective judgments of the location‟s inhabitants. While semi-quantitative

at best, and subject to biases, data of this sort may well be as reliable as any other. It reflects, in

any event, the perceived needs of those for whom the planning is being done. Frequency

projection data from all three sources was used, as appropriate in this Plan. Because all are

subject to considerable uncertainty, the composite data was examined and assigned a relative

level based on the criteria shown in Table 1.2 Frequency Level Criteria.

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Table 1.2 Frequency Level Criteria

Once a hazard‟s magnitude and its frequency have been evaluated, a picture of the over-all risk

severity associated with that hazard emerges. Because the values are necessarily imprecise and

subjective, the risk is visualized by plotting them as shown in Figure 1.3. Here, the frequency is

plotted on the vertical axis (Low at the top to High at the bottom), and magnitude is on the

horizontal axis (Low = 6 to 12, Medium = 13 to 19, and High = 20 to 48). Hazards with the most

severe associated risk, therefore, appear toward the lower right while lowest severity risk hazards

appear near the upper left.

The overall risk severity ranking for Counties will be depicted on a Magnitude/Frequency Table

for each of the respective hazards presented in this regional summary.

Frequency

Ranking Description

HIGH Multiple Times a Year to 5 Years

MEDIUM 5 to 25 Years

LOW 25 Years to Hasn‟t Happened

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2

(High) 3

Figure 1.3 Risk Ranking

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Section 2 Hazard Profiles

Drought

Drought is an expected phase in the climactic cycle of almost any geographical region.

Certainly that is the case in the State of Idaho. Objective, quantitative definitions for drought

exist but most authorities agree that, because of the many factors contributing to it and because

its onset and relief are slow and indistinct, none is entirely satisfactory. According to the

National Drought Mitigation Center, drought “originates from a deficiency of precipitation over

an extended period of time, usually a season or more. This deficiency results in a water shortage

for some activity, group, or environmental sector.” What is clear is that a condition perceived as

“drought” in a given location is the result of a significant decrease in water supply relative to

what is “normal” in that area. It should be noted that water supply is not only controlled by

precipitation (amount, frequency, and intensity), but also by other factors including evaporation

(which is increased by higher than normal heat and winds), transpiration, and human use.

According to the NOAA National Climactic Data Center, much of the State of Idaho most

recently experienced moderate to extreme drought conditions from the years 2000 through 2005.

Drought Emergency Declarations were issued for various counties by the Idaho Department of

Water Resources in the years 2002 through 2005.

Date Declared County/Area Date Declared County/Area

8/6/2003 Bonneville County 5/4/2004 Fremont County




7/10/2007 Bonneville County 7/22/2003 Jefferson County

4/19/2002 Butte County 7/9/2002 Jefferson County




4/29/2003 Butte County 7/24/2003 Lemhi County

5/17/2002 Clark County 5/5/2004 Lemhi County



5/15/2007 Clark County 6/12/2002 Madison County

4/29/2003 Clark County 6/2/2003 Madison County

5/30/2002 Custer County 5/20/2004 Madison County



3/15/2007 Custer County 8/6/2003 Teton County

4/29/2003 Custer County 6/17/2004 Teton County

5/17/2020 Fremont County 6/13/2007 Teton County

Table 2.1 Drought Declarations issued by the Idaho Department of Water Resources

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The data depicted is from the National Weather Service (NWS) and covers the years 1970 to the

present. The Palmer Modified Drought Index (PMDI) is a means of quantifying drought in terms

of moisture demands versus moisture supply. Moisture demands include plant requirements and

water needed for recharge of soil moisture supplies. An allowance is also included for runoff

amounts necessary for recharging both ground water and surface water supplies such as rivers,

lakes, aquifers and reservoirs. The PMDI balances the moisture demands against the moisture

supply available.

The PMDI expresses this comparison of moisture demand to moisture supply on a numerical

scale that usually ranges from positive six to negative six. Positive values reflect excess

moisture supplies while negative values indicate moisture demands in excess of supplies. Table

2.2 below provides the definition of the ranges.

Approximate Cumulative

Frequency %

Category

PMDI Range

> 96 Extreme Wetness > 3.50

90-95 Severe Wetness 2.50 – 3.49

73 – 89 Mild to Moderate Wetness 1.00 – 2.49

28 – 72 Near Normal -1.24 - .099

11 -27 Mild to Moderate Drought -1.25 - -1.99

5 – 10 Severe Drought -2.00 – 2.74

1 – < 4 Extreme Drought < -2.75

Table 2.2

PMDI Classes for Wet and Dry Periods

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Figure 2.1 Idaho Climate Divisions

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-8

-6

-4

-2

0

2

4

6

1970.01

1971.04

1972.07

1973.1

1975.01

1976.04

1977.07

1978.1

1980.01

1981.04

1982.07

1983.1

1985.01

1986.04

1987.07

1988.1

1990.01

1991.04

1992.07

1993.1

1995.01

1996.04

1997.07

1998.1

2000.01

2001.04

2002.07

2003.1

2005.01

2006.04

2007

PMDI Central Mountains (Division 4)

Figure 2.2 PMDI Division 4

-6

-4

-2

0

2

4

6

8

1970

1971

1972

1973

1975

1976

1977

1978

1980

1981

1982

1983

1985

1986

1987

1988

1990

1991

1992

1993

1995

1996

1997

1998

2000

2001

2002

2003

2005

2006

2007

PMDI Northeastern Valleys (Division 8)


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-10

-8

-6

-4

-2

0

2

4

6

8

10

1970

1971

1972

1973

1975

1976

1977

1978

1980

1981

1982

1983

1985

1986

1987

1988

1990

1991

1992

1993

1995

1996

1997

1998

2000

2001

2002

2003

2005

2006

2007

PMDI Central Plains (Division 7)


-10

-8

-6

-4

-2

0

2

4

6

8

10

12

1970

1971

1972

1973

1975

1976

1977

1978

1980

1981

1982

1983

1985

1986

1987

1988

1990

1991

1992

1993

1995

1996

1997

1998

2000

2001

2002

2003

2005

2006

PMDI Upper Snake River Plains (Division 9)


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Impacts

Drought is agriculture‟s most expensive, frequent, and widespread form of natural disaster.

Drought produces a complex web of impacts that spans many sectors of the economy and

reaches well beyond the area experiencing physical drought. This complexity exists because

water is integral to our ability to produce goods and provide services.

Impacts are commonly referred to as direct or indirect. Reduced crop, rangeland, and forest

productivity; increased fire hazard; reduced water levels; increased livestock and wildlife

mortality rates; and damage to wildlife and fish habitat are a few examples of direct impacts.

The consequences of these impacts illustrate indirect impacts. For example, a reduction in crop,

rangeland, and forest productivity may result in reduced income for farmers and agribusiness,

increased prices for food and timber, unemployment, reduced tax revenues because of reduced

expenditures, increased crime, foreclosures on bank loans to farmers and businesses, migration,

and disaster relief programs. Direct or primary impacts are usually biophysical. Conceptually

speaking, the more removed the impact from the cause, the more complex the link to the cause.

In fact, the web of impacts becomes so diffuse that it is very difficult to come up with financial

estimates of damages. The impacts of drought can be categorized as economic, environmental,

or social.

Many economic impacts occur in agricultural and related sectors because of the reliance of these

sectors on surface and subsurface water supplies. In addition to obvious losses in yields in crop

and livestock production, drought is associated with increases in insect infestations, plant

disease, and wind erosion. Droughts also bring increased problems with insects and diseases to

forests, and reduce growth. The incidence of forest and range fires increases substantially during

-8

-6

-4

-2

0

2

4

6

8

101970.01

1971.04

1972.07

1973.1

1975.01

1976.04

1977.07

1978.1

1980.01

1981.04

1982.07

1983.1

1985.01

1986.04

1987.07

1988.1

1990.01

1991.04

1992.07

1993.1

1995.01

1996.04

1997.07

1998.1

2000.01

2001.04

2002.07

2003.1

2005.01

2006.04

2007

PMDI Eastern Highlands (Division 10)


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extended droughts, which in turn places both human and wildlife populations at higher levels of

risk.

Mitigation Actions

The water resources of the Snake River Basin (both surface and ground) are being stressed by

drought, population growth, and increasing demands by agriculture, cities, and recreational

activities. Therefore, the High Country Resource Conservation and Development Council

conducted a winter cloud seeding program to augment snow packs. The target areas were Upper

Snake River Basin and those watersheds draining into Water Basin 31. The program ran from

November 1, 2007 to April 1, 2008 and was contracted out to Clark County and Let it Snow Inc.

Results of Snake River Basin Cloud Seeding 07-08:

IDWR perspective on weather modification said there is conceptually defensible and

documented success. It is difficult to quantify the effectiveness because so many variables exist.

Success of the program relies on the quality of the program as well as its operators. Current

SNOTEL data shows reported areas have experienced more than 100 percent precipitation during

this winter season. With many storms moving though the state, it was a good year to activate the

weather modification project.

The North American Weather Consultants, Inc. prepared results from regression equations

developed for the operational upper Snake River cloud seeding program. The results showed the

northern region ranged from 0.29 to 0.93 inches of additional water content. While the eastern

region ranged from 0.29 to 0.44 inches of additional water content.1

Loss Estimates

Income loss is another indicator used in assessing the impacts of drought because so many

sectors are affected. Reduced income for farmers has a ripple effect. Retailers and others who

provide goods and services to farmers face reduced business. This leads to unemployment,

increased credit risk for financial institutions, capital shortfalls, and loss of tax revenue for local,

State, and Federal government. Less discretionary income affects the recreation and tourism

industries. Prices for food, energy, and other products increase as supplies are reduced. In some

cases, local shortages of certain goods result in the need to import these goods from outside the

stricken region. Hydropower production may be curtailed significantly.

Hazard Evaluation

Drought risk is based on a combination of the frequency, severity, and spatial extent of the

drought (the physical nature of drought) and the degree to which a population or activity is

vulnerable to the effects of drought. The degree of a Region‟s vulnerability depends on the

environmental and social characteristics of the Region and is measured by their ability to

anticipate, cope with, resist, and recover from drought. Society‟s vulnerability to drought is

determined by a wide range of factors, both physical and social, such as demographic trends and

geographic characteristics.

Drought is the most frequent natural hazard in the Region. The losses can be devastating to the

local economy and certainly to individuals. Drought however, is difficult to mitigate. The State

of Idaho Department of Water Resources does have a Drought Management Plan. The Plan

1 http://www.hcountryrcd.org/cloud%20seeding.htm

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looks to managing the effects of Drought on the State‟s Agricultural Community. Other hazards

are exacerbated by Drought especially wildfire. Drought leads to insect infestations and loss of

vegetation damaging range lands and making them more susceptible to wildfire and erosion from

wind.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2

Butte

Clark

Bonneville

Custer

Fremont

Jefferson

Fremont

Madison

Teton

(High) 3

Figure 2.7 Drought Risk Ranking

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Winter Storm

Description

The NWS describes “Winter Storm” as weather conditions that produce heavy snow or

significant ice accumulations. For purposes of this analysis Severe Winter Storm is defined as

any winter condition where the potential exists for a blizzard (winds >= 35mph and

falling/drifting snow frequently reduce visibility < ¼ mile, for 2 hrs or more) heavy snowfall

(valleys 6 inches or more snowfall in 24 hrs mountains 9 inches or more snowfall in 24 hrs), ice

storm, and/or strong winds.

Historical Frequencies

Severe winter storms happen yearly in the Region, with different levels of severity. They have

the potential to be mild or extremely severe. What was, perhaps, the Region‟s most extreme

winter storm event took place in February of 1949. Between February 6 and 15 of that year

there was heavy snow and high winds. Many roads were closed intermittently through the storm

as crews worked to keep snowdrifts clear. Schools were cancelled, no flights left the Idaho Falls

airport and trains were either hours behind or not operating at all. By February 10, higher

temperatures had melted some snow allowing some roads to open and rail traffic to return to

normal. On February 11, however, more snow and wind closed roads and shut down power. By

February 15, nearly all major roads in the region were closed. Many communities were isolated

by the storm. Snow depth was measured at more than 30 inches throughout the storm and winds

were measured at over 50 miles per hour. Two fatalities caused by a snow slide were recorded.

Impacts

The impacts of the very cold temperatures that may accompany a severe winter storm exacerbate

the risks of winter storms. Other life threatening impacts are numerous. Motorists may be

stranded by road closures or may be trapped in their automobiles in heavy snow and/or low

visibility conditions. Bad road conditions cause automobiles to go out of control. People can be

trapped in homes or buildings for long periods of time without food, heat and utilities. Those

who are ill may be deprived of medical care by being stranded or through loss of utilities and

lack of personnel at care facilities. Use of heaters in automobiles and buildings by those who are

stranded may result in fires or carbon monoxide poisoning. Fires during winter storm conditions

are a particular hazard because fire service response is hindered or prevented by road conditions

and because water supplies may be frozen. Disaster Services may also not be available if

telephone service is lost. People who attempt to walk to safety through winter storm conditions

often become disoriented and lost. Downed power lines not only deprive the community of

electricity for heat and light, but pose an electrocution hazard. Death and injury may also occur

if heavy snow accumulation causes roofs to collapse. Fatalities in Idaho due to winter storms are

somewhat unusual, with ten being reported during the ten year period from 1995 through 2004.

Loss Estimates

Economic impacts arise from numerous sources including but not limited to: hindered

transportation of goods and services, flooding due to burst water pipes, forced closing of

businesses, inability of employees to reach the workplace, damage to homes and structures,

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automobiles and other belongings by downed trees and branches and loss of livestock and

vegetation.

Hazard Evaluation

Severe Winter Storms is considered a serious hazard throughout the Region. Of particular

concern is the loss of electrical power during winter storms. In Teton County for example loss of

electrical power during severe winter storms occurs frequently. Teton County as well as Butte

and Custer Counties have only single loop power. When power supplies are lost in these

Counties they must rely on local emergency generators to maintain public protection. In Lemhi

County a similar issue exists. The Lemhi County power supply is limited and during times of

extreme cold Lemhi County experiences electricity “brown outs”.

Other issues tied to Severe Winter Storms include the closure of transportation systems. This is

a concern throughout the Region. Issues with stranded motorists are experienced in Bonneville,

Fremont, Clark, Lemhi, and Custer Counties occasionally.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2 Bonneville

Jefferson

(High) 3

Butte

Clark

Custer

Fremont

Lemhi

Madison

Teton

Figure 2.8 Winter Storm Risk Ranking

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Flooding

Flooding is defined by NWS as “the inundation of normally dry areas as a result of increased

water levels in an established water course.” River flooding, the condition where the river rises

to overflow its natural banks, may occur due to a number of causes including prolonged, general

rainfall, local intense thunderstorms, snowmelt, and ice jams. In addition to these natural events,

there are a number of factors controlled by human activity that may cause or contribute to

flooding. These include dam failure (discussed below), levee failure, and activities that increase

the rate and amount of runoff such as paving, reducing ground cover, and clearing forested areas.

Flooding is a periodic event along most rivers with the frequency depending on local conditions

and controls such as dams and levees. The land along rivers that is identified as being

susceptible to flooding is called the floodplain. The Federal standard for floodplain

management under the National Flood Insurance Plan (NIFP) is the “100-year floodplain.” This

area is chosen using historical data such that in any given year there is a one percent chance of a

“Base Flood” (also known as “100-year Flood” or “Regulatory Flood”). A Base Flood is one

that covers or exceeds the 100-year floodplain. In Idaho, flooding most commonly occurs in the

spring of the year and is caused by snowmelt. Floods occur in Idaho every one to two years and

are considered the most serious and costly natural hazard affecting the State. In the twenty-five

years from 1976 to 2000 there were five Federal and twenty-eight State disaster declarations due

to flooding. The amount of damage caused by a flood is influenced by the speed and volume of

the water flow, the length of time the impacted area is inundated, the amount of sediment and

debris carried and deposited, and the amount of erosion that may take place.

Flooding is a dynamic natural process. Along rivers, streams and coastal bluffs a cycle of

erosion and deposition is continuously rearranging and rejuvenating the aquatic and terrestrial

systems. Although many plants, animals and insects have evolved to accommodate and take

advantage of these ever-changing environments, property and infrastructure damage often occurs

when people develop coastal areas and floodplains and natural processes are altered or ignored.

Flooding can also threaten life, safety and health, and often results in substantial damage to

infrastructure, homes, and other property. The extent of damage caused by a flood depends on

the topography, soils and vegetation in an area, the depth and duration of flooding, velocity of

flow, rate of rise, and the amount and type of development in the floodplain.

Floodplain Management

An important part of being an NFIP community is the availability of low cost flood insurance for

those homes and businesses within designated floodplains, or in areas that are subject to flooding,

but that are not designated as Special Flood Hazard Areas.

Overall participation by individuals and business in the NFIP appears to be low. Potential reasons for continuing low participation in the program are:

Current cost of insurance is prohibitive.

A lack of knowledge about the existence of the availability of low cost flood insurance.

Home and business owners maybe unaware of their vulnerability to flood events.

The last two reasons can be addressed through public education. The first could be addressed by

all communities in the Counties taking advantage of the Community Rating System (CRS). To

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20

encourage communities to go beyond the minimum requirements and further prevent and

protect against flood damage, the NFIP established the CRS. To qualify for CRS, communities

can do things like make building codes more rigorous, maintain drainage systems, and inform

residents of flood risk. In exchange for becoming more flood ready, the CRS community's

residents are offered discounted premium rates. Based on the community's CRS ratings, they

can qualify for up to a 45% discount of annual flood insurance premiums. Neither the Counties,

nor any of the incorporated cities participate in the Community Rating System.

As depicted in the Figure 2.9 all

of the Counties in the Region

are currently participating in the

National Flood Insurance

Program however, there are

several local jurisdictions that

are not. There is a need to

increase participation in the

NFIP to ensure that citizens

throughout the Region are

afforded the opportunity to

protect their properties in flood

prone areas.

Figure 2.9 NFIP Status

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Figure 2.10 100 Year Floodplain FIRM

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River or Stream Flooding

Description

River flooding, the condition where the river rises to overflow its natural banks, may occur due

to a number of causes including prolonged, general rainfall, locally intense thunderstorms,

snowmelt, and ice jams.


The following table shows the frequency of flood events at locations along the Teton, Henry‟s

Fork, and Snake Rivers. These locations are the stream gauges that the National Weather Service

monitors for flooding. It is noted that the frequencies on the Snake River did drop drastically

from 1958 to the present, because of the construction of Palisades Dam. Also, the first flood on

the Henry‟s fork occurred in 1970, even though there are 89 years on record.

River Gauge

Location

Flood Stage

(CFS)

Years on

Record

Number of

Flood Events Frequency

Return

Interval

Henry's Fork St. Anthony 9,100 89 6 6.74% 14.83

Henry's Fork Rexburg 7,900 99 32 32.32% 3.09

Snake River Heise 25,000 98 29 29.59% 3.38

Snake River Shelley 25,400 93 26 27.96% 3.58

Teton River Driggs 2,900 47 1 2.13% 47.00

Teton River St. Anthony 4,900 105 6 5.71% 17.50

Table 2.3 Historical Frequencies of flood events

The year 1997 was probably the worst flood year on record. Rapid melt of a record snowmelt

led to flooded rivers throughout southern Idaho. The Snake River Basin received significant

snowfall during the winter of 1996-97, and in higher elevations the snow pack exceeded 250% of

normal, causing above normal runoff during the spring melt. Reservoir flows were increased to

allow storage capacity, producing the highest flows on the Snake River in 70 years. During

June, the spring snowmelt caused extensive flooding along 225 miles of the Snake River and

many of its tributaries, from Roberts to Blackfoot. In places, floodwaters ran as far as a mile

Northeastern Idaho


23

away from the river and 5' deep. Damage was extensive to numerous roads, canals, farmland

and over 300 homes.

A Federal Disaster was declared on July 7, 1997, for seven counties in SE Idaho: Bingham,

Bonneville, Fremont, Jefferson, Madison, Butte and Custer. Approximately 500 people were

evacuated in Jefferson and Bingham counties; more than 50,000 acres of agricultural land was

flooded; and over nearly $1.3 million in grants and loans had been distributed2.

Impacts

Human death and injury sometimes occur as a result of river flooding but are not common.

Human hazards during flooding include drowning, electrocution due to downed power lines,

leaking gas lines, fires and explosions, hazardous chemicals and displaced wildlife. Economic

loss and disruption of social systems are often enormous. Floods may destroy or damage

structures, furnishings, business assets including records, crops, livestock, roads and highways,

and railways. They often deprive large areas of electric service, potable water supplies,

wastewater treatment, communications, and many other community services including medical

care, and may do so for long periods of time.

Loss Estimates

County Number of Parcels

Value of

Individual

Parcels

Max Parcel

Value

Bonneville 4,993.00 588,614,136.00 15,588,197.00

Butte 971.00 40,721,927.00 1,066,240.00

Clark HAZUS HAZUS HAZUS

Custer 1,981.00 96,369,135.00 1,628,210.00

Fremont 2,447.00 127,637,480.00 1,500,370.00

Jefferson 1,964.00 47,072,050.00 848,660.00

Lemhi 1,484.00 89,203,873.00 2,025,828.00

Madison 4,573.00 204,340,206.00 7,222,362.00

Teton 1,672.00 106,062,883.00 3,520,000.00

Total 20,085.00 N/A 15,588,197.00

Table 2.4 Loss Estimates

2 http://www.bhs.idaho.gov/local/counties/madison.htm

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24

Figure 2.11 HAZUS 100 Year Floodplain

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25

Hazard Evaluation

River and Stream Flooding occurs in all of the Counties in the Region. Flooding in the Region

occurs frequently along the North and South Forks of the Snake River, the Teton River, the

Salmon and Lemhi Rivers, and occasionally along the Big and Little Lost Rivers. Flooding for

the most part is caused by spring runoff. Flooding in the Region also occurs frequently along

intermittent streams due to spring melt and runoff from severe thunderstorms. Ice Jam flooding

occurs along the Salmon River, especially below the City of Salmon and in Butte County along

Antelope Creek.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2

Butte

Custer

Jefferson

Lemhi

(High) 3 Clark Teton

Bonneville

Fremont

Madison

Figure 2.12 River/Stream Flooding Risk Ranking

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26

Dam Failure

Description

Dam failure is the unintended release of impounded waters. Dams can fail for one or a

combination of the following reasons:

Overtopping caused by floods that exceed the capacity of the dam.

Deliberate acts of sabotage.

Structural failure of materials used in dam construction.

Poor design and/or construction methods.

Movement and/or failure of the foundation supporting the dam.

Settlement and cracking of concrete or embankment dams.

Piping and internal erosion of soil in embankment dams.

Inadequate maintenance and upkeep.

Failures may be categorized into two types; component failure of a structure that does not result

in a significant reservoir release, and uncontrolled breach failure that leads to a significant

release. With an uncontrolled breach failure of a manmade dam there is a sudden release of the

impounded water, sometimes with little warning. The ensuing flood wave and flooding have

enormous destructive power. The Idaho Department of Water Resources (IDWR) is responsible

for dam safety in this State. The program is described as follows (from the “Dam Safety

Program,” IDWR web site).3

Dams 10 feet or higher or which store more than 50 acre feet of water are regulated by the Idaho

Department of Water Resources (as are mine tailings impoundment structures). Idaho currently

has 546 water storage dams and 21 mine tailings structures that are regulated by IDWR for

safety. The Dam Safety Section inspects these dams or tailings structures every other year unless

one has a particular problem. Copies of all inspection reports for each of the dams and tailing

structures are available at the IDWR State Office in Boise. Inspection reports are also available

at the four IDWR Regional Offices for dams and tailing structures located in their specific

regions.

Dam Classifications

Each dam inspected by Idaho Water Resources is given both a size and risk classification.

Size Classification

Small – 3: Twenty (20) feet high or less and a storage capacity of less than one hundred (100)

acre feet of water.

Intermediate – 2: More than twenty (20) but less than forty (40) feet high or with a storage

capacity of one hundred (100) to four thousand (4,000) acre feet of water.

Large – 1: Forty (40) feet high or more or with a storage capacity of more than four thousand

(4,000) acre feet of water.

3 http://www.idwr.state.id.us/water/stream_dam/dams/dams.htm

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27

Risk Classification

This classification is used by IDWR to classify potential losses and damages anticipated in

down-stream areas that could be attributable to failure of a dam during typical flow conditions.

Low Risk – 3: No permanent structures for human habitation; Minor damage to land, crops,

agricultural, commercial or industrial facilities, transportation, utilities or other public facilities

or values.

Significant Risk – 2: No concentrated urban development, one (1) or more permanent structures

for human habitation which are potentially inundated with flood water at a depth of two (2) ft. or

less or at a velocity of two (2) ft. per second or less. Significant damage to land, crops,

agricultural, commercial or industrial facilities, loss of use and/or damage to transportation,

utilities or other public facilities or values.

High Risk – 1: Urban development, or any permanent structure for human habitation which are

potentially inundated with flood water at a depth of more than two (2) ft. or at a velocity of more

than two (2) ft. per second. Major damage to land, crops, agricultural, commercial or industrial

facilities, loss of use and/or damage to transportation, utilities or other public facilities or values.

Purposes Categories:

N-Industrial, B-Mining, O-Other, C-Commercial, P-Power, D-Domestic, Q-Fire Protection, E-

Erosion Control, F-Flood Control, S-Stockwater, G-Wildlife Protection, T-Mine Tailings, H-Fish

Propagation, I-Irrigation, J-Stockwater and Irrigation, K-Domestic, Stock and Irrigation, L-

Domestic and Irrigation, M-Municipal Supply

Dam Type

Earth- Earth Fill, Rock- Rock Filled, CNGRV- Concrete Gravity, CNAR-Concrete Arch,

MCNAR-Multiple Concrete Arch, TMCRB-Timber Crib, SLBT-Slab and Buttress, RKMAS-

Rock Masonry, Metal-Metal Sheet Pile, AUXDAM-Auxiliary Dam

There are 4 large dams in the Region that have the potential to impact multiple counties if they

were to fail: Palisades Dam in Bonneville County, Ririe Dam in Bonneville County, Island Park

Dam in Fremont County, and Mackay Dam in Custer County. The following table summarizes

the size and type of these dams.

Name Stream Purpose Risk

Category

Size

Category

Type Storage

Capacity

(Acre Ft.)

Height

(Ft.)

Island Park Henry‟s Fork L 1 1 Earth 127,646 73

Mackay Big Lost

River J 1 1 Earth 45,000 67

Palisades Snake River IFP 1 1 Earth 1,410,000 248

Ririe Willow Creek IF 1 1 Rock 100,500 169

Table 2.5 Size and Type of Dams

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28

Figure 2.13 Island Park Dam Failure

Northeastern Idaho


29

Figure 2.14 Palisades Dam Failure

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30

Figure 2.15 Ririe Dam Failure Inundation Zone

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31

Figure 2.16 Mackay Dam Failure Inundation Zone

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32


Dam Failure, 5 June 1976

Teton Dam, a 305-foot high earthfilled dam across the Teton River in Madison County, southeast

Idaho, failed completely and released the contents of its reservoir at 11:57 AM on June 5, 1976.

Failure was initiated by a large leak near the right (northwest) abutment of the dam, about 130

feet below the crest. The dam, designed by the U.S. Bureau of Reclamation, failed just as it was

being completed and filled for the first time.

Oblique aerial view northeast and upstream of Teton Dam site as it looks

today. The right (northwest) abutment is between the spillway and the present

course of the river. All that remains of the original dam is the terraced,

pyramid shaped monolith in the center of the canyon in the center of the

photograph. The cut on the right was made after the failure to determine the

structure of the embankment. 4

Eyewitnesses noticed the first major leak between 7:30 and 8:00 AM, June 5, although two days

earlier engineers at the dam observed small springs in the right abutment downstream from the

toe of the dam. The main leak was flowing about 20-30 cfs from rock in the right abutment near

the toe of the dam and above the abutment-embankment contact. The flow increased to 40-50 cfs

by 9 AM. At about the same time, 2 cfs seepage issued from the rock in the right abutment,

approximately 130 feet below the crest of the dam at the abutment-embankment contact.

Between 9:30 and 10 AM, a wet spot developed on the downstream face of the dam, 15 to 20

feet out from the right abutment at about the same elevation as the seepage coming from the right

abutment rock. This wet spot developed rapidly into seepage, and material soon began to slough,

4 Photo by U.S. Bureau of Reclamation

Figure 2.17 Teton Dam after Failure

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33

and erosion proceeded back into the dam embankment. The water quantity increased continually

as the hole grew. Efforts to fill the increasing hole in the embankment were futile during the

following 2 to 2 1/2 hour period until failure. The sheriff of Fremont County (St. Anthony,

Idaho) said that his office was officially warned of the pending collapse of the dam at 10:43 AM

on June 5. The sheriff of Madison County, Rexburg, Idaho, was not notified until 10:50 AM on

June 5. He said that he did not immediately accept the warning as valid but concluded that while

the matter was not too serious, he should begin telephoning people he knew who lived in the

potential flood path.

The dam breached at 11:57 AM when the crest of the embankment fell into the enlarging hole

and a wall of water surged through the opening. By 8:00 PM the flow of water through the

breach had nearly stabilized. Downstream the channel was filled at least to a depth of 30 feet for

a long distance. About 40 percent of the dam embankment was lost, and the powerhouse and

warehouse structure were submerged completely in debris.

Loss Estimates

The following table shows loss estimates for the three dam failure scenarios. These numbers

were generated by using a GIS overlay operation using parcels and floodplains.

County Dam Number of Parcels

Max Value

of Individual

Parcels

Total Value Mean Value

Fremont Island Park 2,091 371,590 68,343,900 43,984

Madison Island Park 1,092 648,499 26,033,914 23,840

Jefferson Island Park 1,108 595,370 32,792,760 29,596

Total Island Park 4,291 N/A 127,170,574 32,473

Custer Mackay Dam 1,568 873,690 60,365,955 38,498

Butte Mackay Dam 1,469 375,640 18,341,363 12,485

Total Mackay Dam 3,037 N/A 78,707,318 25,492

Bonneville Palisades 9,506 45,241,168 1,118,137,288 117,624

Jefferson Palisades 10,508 851,450 85,176,686 8,105

Madison Palisades 3,826 660,814 110,549,634 28,894

Total Palisades 23,840 N/A 1,313,863,608 51,541

Bonneville Ririe 33,112 53,290,669 4,494,700,454 135,742

Table 2.6 Loss Estimates

Hazard Evaluation

Catastrophic failure of large earth filled dams is of concern in the Region. In 1976 the Teton

Dam failed bringing devastation to the areas below the dam. There are five dams, listed above,

which have the potential to cause significant property loss if they failed. Of special concern

because of their proximity to large populations are the Ririe, Mackay, and Island Park Dams.

Other dams of concern include the Grassly Lake Dam, the Ashton Dam, and the Palisades Dam.

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34

The Palisades Dam is the largest in total capacity in the Region however; the Ririe Dam has the

potential to cause the most harm.

The dams are unmanned for the most part. Surveillance systems on the dams are basically non-

existent. Failure to notify downstream populations within a short time (2-10 minutes) could

result in loss of life.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

Clark Teton

Butte

Jefferson

Lemhi

Madison

(Medium) 2

(High) 3

Bonneville

Custer

Fremont

Figure 2.18 Dam Failure Risk Ranking

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35

Earthquake

Description

The U.S. Geological Survey (USGS) defines earthquake as: “Ground shaking caused by the

sudden release of accumulated

strain by an abrupt shift of rock

along a fracture in the Earth or by

volcanic or magmatic activity, or

other sudden stress changes in the

Earth.” The hazards associated

with earthquake are essentially

secondary to ground shaking (also

called seismic waves) which may

cause buildings to collapse,

displacement or cracking of the

earth‟s surface, flooding as a

result of damage to dams or

levees, and fires from ruptured gas

lines, downed power lines and

other sources. Earthquakes cause

both vertical and horizontal

ground shaking which varies both

in amplitude (the amount of

displacement of the seismic

waves) and frequency (the number

of seismic waves per unit time),

usually lasting less than thirty

seconds. Earthquakes are

measured both in terms of their

inherent “magnitude” and in terms

of their local “intensity.”

The magnitude of an earthquake is essentially a relative estimate of the total amount of seismic

energy released and may be expressed using the familiar “Richter Scale” or using the “moment

magnitude scale” now favored by most technical authorities. Both the Richter Scale and the

moment magnitude scale are based on logarithmic formula meaning that a difference of one unit

on the scales represents about a thirty-fold difference in amount of energy released (and,

therefore, potential to do damage). On either scale, significant damage can be expected from

earthquakes with a magnitude of about 5.0 or higher. What determines the amount of damage

that might occur in any given location, however, is not the magnitude of the earthquake but the

intensity at that particular place. Earthquake intensity decreases with distance from the

earthquake‟s “epicenter” (its focal point) but also depends on local geologic features such as

depth of sediment and bedrock layers. Intensity is most commonly expressed using the

“Modified Mercalli Intensity Scale.” This measure describes earthquake intensity on an

arbitrary, descriptive, twelve degree scale (expressed as Roman numerals from I to XII) with

significant damage beginning at around level VII. Mercalli intensity is assigned based on

Figure 2.19 Idaho Faults Map

Northeastern Idaho


36

eyewitness accounts. More quantitatively, intensity may be measured in terms of “peak ground

acceleration” (PGA) expressed relative to the acceleration of gravity (g) and determined by

seismographic instruments.

While Mercalli and PGA intensities are arrived at differently, they correlate reasonably well.

While the locations most susceptible to earthquakes are known, there is little ability to predict an

earthquake in the short term. The Figure 2.20 shows the potential for spectral acceleration by

census tract for the Nine County Region. Though the epicenters of earthquakes cluster in Custer

and Lemhi Counties, the highest probability of shaking is along the eastern border of the Region.


Since 1960 there have been 137 recorded earthquakes with epicenters in the region of a

magnitude 4.0 or greater. The majority of those earthquake epicenters are in Custer, Lemhi, and

Bonneville Counties. It can be expected that an earthquake of at least a magnitude 4.0 will occur

within the Region on a yearly basis.

The two largest earthquakes that have affected the Region were the 1959 Hebgen Lake

earthquake, and the 1983 Borah Peak earthquake. The Figure 2.21 and 2.22 show the felt

intensities of these earthquakes according to the Modified Mercalli Intensity Scale.

Northeastern Idaho


37

Figure 2.20 Earthquake Risk

Northeastern Idaho


38

Figure 2.21 Hebgen Lake Earthquake 1959

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39

The Hebgen Lake earthquake caused 28 fatalities and about $11 million in damage to highways

and timber. It is characterized by extensive fault scarps, subsidence and uplift, a massive

landslide, and a seiche in Hebgen Lake. A maximum MM intensity X was assigned to the fault

scarps in the epicentral area. The instrumental epicenter lies within the region of surface faulting.

Areas of perceptibility, maximum intensity, and Richter magnitude all were larger for this

earthquake than for any earlier earthquake on record in Montana (from May 1869).

The most spectacular and disastrous effect of the earthquake was the huge avalanche of rock, soil

and trees that cascaded from the steep south wall of the Madison River Canyon. This slide

formed a barrier that blocked the gorge and stopped the flow of the Madison River and, within a

few weeks, created a lake almost 53 meters deep. The volume of material that blocked the

Madison River below Hebgen Dam has been estimated at 28 - 33 million cubic meters. Most of

the 28 deaths were caused by rockslides that covered the Rock Creek public campground on the

Madison River, about 9.5 kilometers below Hebgen Dam.

New fault scarps as high as 6 meters formed near Hebgen Lake. The major fault scarps formed

along pre-existing normal faults northeast of Hebgen Lake. Subsidence occurred over much of an

area that was about 24 kilometers north-south and about twice as long east-west. As a result of

the faulting near Hebgen Lake, the bedrock beneath the lake was permanently warped, causing

the lake floor to drop and generate a seiche. Maximum subsidence was 6.7 meters in Hebgen

Lake Basin. About 130 square kilometers subsided more than 3 meters, and about 500 square

kilometers subsided more than 0.3 meters. The earth-fill dam sustained significant cracks in its

concrete core and spillway, but it continued to be an effective structure.

Many summer houses in the Hebgen Lake area were damaged: houses and cabins shifted off

their foundations, chimneys fell, and pipelines broke. Most small-unit masonry structures and

wooden buildings along the major fault scarps survived with little damage when subjected only

to vibratory forces. Roadways were cracked and shifted extensively, and much timber was

destroyed. Highway damage near Hebgen Lake was due to landslides slumping vertically and

flowing laterally beneath pavements and bridges, which caused severe cracks and destruction.

Three of the five reinforced bridges in the epicentral area also sustained significant damage.

High intensities were observed in the northwest section of Yellowstone National Park. Here, new

geysers erupted, and massive slumping caused large cracks in the ground from which steam

emitted. Many hot springs became muddy.

On the basis of vibration damage (and excluding geologic effects), damage to buildings along the

fault zone was singularly unspectacular (MM intensity VIII at places, intensity VII generally).

Minor damage occurred throughout southern Montana, northeast Idaho, and northwest

Wyoming. Felt as far as Seattle, Washington, to the west; Banff, Canada, to the north;

Dickinson, North Dakota, to the east; and Provo, Utah, to the south. This area includes nine

Western States and three Canadian Provinces. Aftershocks continued for several months.

Northeastern Idaho


40

Figure 2.22 Borah Peak Earthquake 1983

Northeastern Idaho


41

The Borah Peak earthquake is the largest ever recorded in Idaho - both in terms of magnitude

and in amount of property damage. It caused two deaths in Challis, about 200 kilometers

northeast of Boise, and an estimated $12.5 million in damage in the Challis-Mackay area. A

maximum MM intensity IX was assigned to this earthquake on the basis of surface faulting.

Vibrational damage to structure was assigned intensities in the VI to VII range.

Spectacular surface faulting was associated with this earthquake - a 34-kilometer-long

northwest-trending zone of fresh scarps and ground breakage on the southwest slope of the Lost

River Range. The most extensive breakage occurred along the 8-kilometer zone between West

Spring and Cedar Creek. Here, the ground surface was shattered into randomly tilted blocks

several meters in width. The ground breakage was as wide as 100 meters and commonly had four

to eight en echelon scarps as high as 1-2 meters. The throw on the faulting ranged from less than

50 centimeters on the southern-most section to 2.7 meters south of Rock Creek at the western

base of Borah Peak.

Other geologic effects included rockfalls and landslides on the steep slopes of the Lost River

Range, water fountains and sand boils near the geologic feature of Chilly Buttes and the Mackay

Reservoir, increase or decrease in flow of water in springs, and fluctuations in well water levels.

A temporary lake was formed by the rising water table south of Dickey.

The most severe property damage occurred in the towns of Challis and Mackay, where 11

commercial buildings and 39 private houses sustained major damage and 200 houses sustained

minor to moderate damage.

At Mackay, about 80 kilometers southeast of Challis, most of the commercial structures on Main

Street were damaged to some extent; building inspectors condemned eight of them. Damaged

buildings were mainly of masonry construction, including brick, concrete block, or stone. Visible

damage consisted of severe cracking or partial collapse of exterior walls, cracking of interior

walls, and separation of ceilings and walls at connecting corners. About 90 percent of the

residential chimneys were cracked, twisted, or collapsed.

At Challis, less damage to buildings and chimneys was sustained, but two structures were

damaged extensively: the Challis High School and a vacant concrete-block building (100 years

old) on Main Street. Many aftershocks occurred through 1983. Also felt in parts of Montana,

Nevada, Oregon, Utah, Washington, Wyoming, and in the Provinces of Alberta, British

Columbia, and Saskatchewan, Canada.

Impacts

Earthquakes are capable of catastrophic consequences, especially in urban areas. Worldwide,

earthquakes have been known to cost thousands of lives and enormous economic and social

losses. In minor earthquakes, damage may be done only to household goods, merchandise, and

other building contents and people are occasionally injured or killed by falling objects. More

violent earthquakes may cause the full or partial collapse of buildings, bridges and overpasses,

and other structures. Fires due to broken gas lines, downed power lines, and other sources are

common following an earthquake and often account for much of the damage. Economic losses

arise from destruction of structures and infrastructure, interruption of business activity, and

innumerable other sources. Utilities may be lost for long periods of time and all modes of

transportation may be disrupted. Disaster Services including medical may be both disabled and

overwhelmed. In addition to broken gas lines, other hazardous materials may be released.

Northeastern Idaho


42

Loss Estimates

The Region was affected by both the Hebgen Lake earthquake (in Montana) in 1959 and the

Borah Peak earthquake (in Custer County Idaho) in 1983, which were among the largest in the

United States in the past fifty years. These two events combined caused thirty deaths and cost

more than twenty million dollars in losses in spite of having been centered in relatively remote

locations.

The following loss estimates were generated using HAZUS-MH MR2. A level 1 analysis was

performed on a probabilistic magnitude 7 earthquake with a 100 year return frequency for the

entire area within 9 County Region. A level 1 analysis is a screen level analysis to determine if

additional analysis maybe required for specific locations. A level 2 analysis can then be run for

specific locations and structures.

Building Damage

HAZUS estimates that about 1,273 buildings will be at least moderately damaged. This is over

2.00 % of the total number of buildings in the Region. There are an estimated 5 buildings that

will be damaged beyond repair. The definition of the „damage states‟ is provided in Volume 1:

Chapter 5 of the HAZUS technical manual.

Essential Facility Damage

Before the earthquake, the Region had 455 hospital beds available for use. On the day of the

earthquake, the model estimates that only 433 hospital beds (95.00%) are available for use by

patients already in the hospital and those injured by the earthquake. After one week, 98.00% of

the beds will be back in service. By 30 days, 100.00% will be operational.

Economic Loss

The total economic loss estimated for the earthquake is $97.56M (millions of dollars), which

includes building and lifeline related losses based on the region's available inventory.

Building Related Economic Loss

The building losses are broken into two categories: direct building losses and business

interruption losses. The direct building losses are the estimated costs to repair or replace the

damage caused to the building and its contents. The business interruption losses are the losses

associated with inability to operate a business because of the damage sustained during the

earthquake. Business interruption losses also include the temporary living expenses for those

people displaced from their homes because of the earthquake.

The total building-related losses were 61.93 (millions of dollars); 14 % of the estimated losses

were related to the business interruption of the Region. By far, the largest loss was sustained by

the residential occupancies which made up over 54 % of the total loss.

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43

Hazard Evaluation

Damaging earthquakes have occurred twice in the Region in modern history. Small earthquakes

occur annually in all the Counties in the Region except Jefferson and Madison. Damage from

these earthquakes is minor. Shaking from earthquakes in the Region can be felt in Jefferson and

Madison Counties therefore the entire Region has the potential to be impacted by an earthquake

centered in the Region.

The intermountain earthquake belt transects Bonneville and Teton Counties on their eastern

border, Fremont County and Clark County on their northern border and transverses Lemhi and

Custer Counties terminating in Custer County. Jurisdictions should consider taking seismic

protective measures when upgrading or install new infrastructure in the Region.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

Jefferson

Madison

(Medium) 2

Clark

Butte

Bonneville

Custer

Fremont

Lemhi

Teton

(High) 3

Figure 2.23 Earthquake Risk Ranking

Northeastern Idaho


44

Wildfire

Description

Wildfire is defined by the USDA Forest service as, “A fire naturally caused or caused by

humans, that is not meeting land management objectives.5” It is generally thought of as an

uncontrolled fire involving vegetative fuels occurring in wildland areas. Such fires are

classified for hazard analysis purposes as either “Wildland” or “Wildland Urban Interface” fires.

Wildland fires occur in areas that are undeveloped except for the presence of roads, railroads and

power lines while Wildland Urban Interface (WUI) fires occur where structures or other human

development meets or is intermingled with the wildland or vegetative fuels. Wildland fire is

currently considered a natural and necessary component of wildland ecology and, as such, is

most often allowed to progress to the extent that it does not threaten inhabited areas or human

interests and well-being. At the Wildland Urban Interface (WUI), vigorous attempts are made

to control fires but this becomes an increasingly difficult challenge as more and more

development for recreational and living purposes takes place in wildland areas. Some wildland

fires are ignited naturally (almost exclusively by lightning) but most ignitions are a result of

human activities, either careless or intentional. The rapidity with which a wildland fire spreads

and the intensity with which it burns is controlled by a number of factors including:

Weather - wind speed and direction, temperature, precipitation

Terrain – fires burn most rapidly upslope

Type of vegetation

Condition of vegetation - dryness

Fuel load – the amount and density of vegetation

Human attempts to suppress

In Idaho, fire was once an integral function of the majority of ecosystems. The seasonal cycling

of fire across the landscape was as regular as the July, August and September lightning storms

plying across the canyons and mountains. Depending on the plant community composition,

structural configuration, and buildup of plant biomass, fire resulted from ignitions with varying

intensities and extent across the landscape. Shorter return intervals between fire events often

resulted in less dramatic changes in plant composition.6 The fires burned from 1 to 47 years

apart, with most at 5- to 20-year intervals.7 With infrequent return intervals, plant communities

tended to burn more severely and be replaced by vegetation different in composition, structure,

and age.8 Native plant communities in this region developed under the influence of fire, and

adaptations to fire are evident at the species, community, and ecosystem levels. Fire history data

(from fire scars and charcoal deposits) suggest fire has played an important role in shaping the

vegetation in the Columbia Basin for thousands of years.9

The mean fire return presented in Figure 2.24 depicts the areas within the Region that are at the

highest risk for wildfire based on fuel type, slope, aspect, and cover density. The mean fire

5 http://www.fs.fed.us/fire/fireuse/education/terms/fire_terms_pg5.html 6 Johnson 1998 7 Barrett 1979 8 Johnson et al, 1994 9 Steele et al, 1986, Agee 1993

Northeastern Idaho


45

return interval takes into account fire started by natural processes, i.e., lightning. Fire started by

humans is not taken into account by this model. Figure 2.25 illustrates the Regional Wildland

Urban Interface.


Wildland fires occur every year in the 9 County Region. Many of those fires cross county

boundaries, and therefore become regional in nature. According to the BLM there were 3,732

wildland fires from 1983 to 2002.

Impact

Wildland fires threaten the lives of anyone in their path including hikers, campers and other

recreational users and, where suppression efforts are made, firefighters. Enormous volumes of

smoke and airborne particulate materials are produced that can affect the health of persons for

many miles downwind. Nearer to the fire, smoke reduces visibility, disrupting traffic and

increasing the likelihood of highway accidents. As a result of wildland fire there may be

changes in water quality in the area and erosion rates may increase along with increased rainfall

runoff and flash flood threat, and decreased rainfall interception and infiltration. Indirect

impacts include losses to tourism, recreational and timber interests and loss of wildlife habitat.

Wildland Urban Interface fires have most or all of the above impacts as well as those of

structural fires including injury and loss of life, loss of structures and contents. Agricultural

losses may also be sustained including livestock, crops, fencing and equipment.

Northeastern Idaho


46

Figure 2.24 Mean Fire Return Interval

Northeastern Idaho


47

Figure 2.25 Wildland Urban Interface

Northeastern Idaho


48

Loss Estimates

County Number of Parcels Max Individual

Parcel Value Total Parcel Value Specific Area

Bonneville 37 $103,547 $119,555 Zone 1

Bonneville 127 $377,370 $5,457,866 Zone 2

Bonneville 548 $510,540 $16,634,793 Zone 3

Bonneville 26 $0 $0 Zone 4

Bonneville 229 $1,120,257 $22,679,052 Zone 5

Bonneville 88 $159,784 $1,283,873 Zone 6

Bonneville 1,084 $938,760 $65,113,389 Zone 7

Bonneville 266 $571,857 $3,125,926 Zone 8

Bonneville 2,405 N/A $114,414,454 Total

Butte 2,452 $1,066,240 $21,335,858 Total

Custer 8,066 $1,628,210 $332,082,265 Total

Fremont 14,351 $1,500,370 $549,177,583 Total

Jefferson 2,076 $1,989,500 $141,369,512 Total

Lemhi 9,746 $3,326,866 $458,784,542 Total

Madison 706 $562,188 $3,982,136 Zone1

Madison 1,124 $660,814 $27,689,873 Zone2

Madison 668 $648,499 $17,795,830 Zone3

Madison 609 $570,817 $18,477,128 Zone4

Madison 109 $122,559 $1,182,380 Zone5

Madison 3,216 N/A $69,127,347 Total

Teton 3,144 $6,980,560 $48,826,426 Total

Clark Not Available

Regional Total 45,456 $6,980,560 $1,735,117,987 Total

There are 45,456 private property parcels in the Region that lie within the Wildland Urban

Interface areas. The total value of all private property located in the defined Wildland Urban

Interface in the Region is $1,735,117, 987. The highest value of any individual parcel in the

Region that lies within the Wildland Urban Interface is located in Teton County and is valued at

$6,980,560.

Table 2.7 Wildfire Loss Estimates

Northeastern Idaho


49

Hazard Evaluation

There is a significant risk to wildfire in the Region. Wildfires occur annually in all Counties

within the Region. Wildfires are caused most often by lightning however, there is also a large

number of fires started annually by humans. Wildfire in the Region is exacerbated by insect

infestations and drought. Wildfires disregard jurisdictional boundaries and therefore are

typically responded to regionally by State, Federal, and local resources. Fuel reduction projects

on the boundaries of individual Counties should be considered.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2

Fremont

Madison

Teton

(High) 3

Clark

Butte

Bonneville

Custer

Jefferson

Lemhi

Figure 2.26 Wildfire Risk Ranking

Northeastern Idaho


50

Nuclear Event

Description

A “nuclear event” is defined as an incident involving a nuclear reaction; nuclear fission or

nuclear fusion. Such an incident must involve “fissionable” materials, defined as materials

containing isotopes with nuclei capable of splitting. Further, the most probable incidents

involve “fissile” materials, defined as materials containing isotopes capable of sustaining a

nuclear fission chain reaction. Such reactions release heat, radiation, and radioactive

contamination in extremely large quantities relative to the amount of material reacting.

Examples of nuclear events include nuclear weapons detonations, nuclear reactor incidents, and

nuclear (fissile) material production, handling or transportation incidents. A nuclear detonation

as a part of an attack scenario is, perhaps, the ultimate technological disaster. The hazards are

well-known and vividly described in FEMA publications10

. They include shock wave,

enormous heat, and the spread of fallout (radioactive contamination). Other nuclear events

would not involve a nuclear blast, but still have the potential to produce widespread and long-

term consequences as exemplified by the 1986 Chernobyl accident11

. Of primary concern is the

release of radioactive contamination in the form of airborne gases and particulate material. This

radioactive material has the potential to travel great distances and particulate material eventually

is deposited in the environment and incorporated into the food chain. Such contamination may

remain hazardous for many years. Direct radiation exposure is also a hazard in relatively close

proximity to a nuclear event as is exposure to high thermal energy. Nuclear events are virtually

always caused by intentional or unintentional human actions.

The Idaho National Laboratory poses a credible hazard to most western parts of the Region. The

locations of the INL and of the RTC facility within the Site boundary are shown in Figure 8.1.1.

Table 8.1.2, provides the Protective Action Distance for a radiological release from the RTC

facility as 115 km (approximately 69 miles). This indicates a threat to crops and grazing lands in

western portions of the Region.

10 http://www.fema.gov/areyouready/nuclear_blast.shtm 11 http://www.iaea.org/NewsCenter/Focus/Chernobyl/index.html

Northeastern Idaho


51

Figure 2.27 Location of the INL and RTC facility

Northeastern Idaho


52

INL Hazards Assessment Maximum Protective Action Distances (PAD)

Facility Non-Rad PAD Rad PAD

Research Center (IRC) 0.1 km None

Radioactive Waste Management

Complex (RWMC) None 15 km

Reactor Technology Complex (RTC) 7.8 km 115 km

Idaho Nuclear Technology and

Engineering Center (INTEC) 1.6 km 16 km

Central Facilities Area (CFA) 0.5 km None

Transportation * *

Materials and Fuels Complex (MFC) 1.7 km 4.5 km

Area North (TAN) ** 0.03 km

* INL asserts that associated transportation activity is within “normal” limits for highway traffic and uses the DOT

ERG for its planning basis.

** Unclear but well within INL Site boundary

Table 2.8

INL Hazards Assessment Maximum Protective Action Distances

Source – U. S. Department of Energy Idaho Operations Office

Northeastern Idaho


53


There are no recorded nuclear events in the region

Impacts

While the INL does not pose a direct, life-threatening threat, a portion of the region lies within

the 69-mile ingestion pathway planning zone of the INL Reactor Technology Complex. In this

zone, direct, human radiological and contamination exposure is not a serious concern. There is,

however, a long-term threat to the food supply because vegetables, fruit, trees, and grains may

take up radionuclides from the soil. Radionuclides may also be ingested by livestock, wild game

and fish that may then enter the human food chain.

In the event of a serious radiological release from that facility, food production, processing and

marketing facilities within the planning zone could be affected.

There are two types of responses intended to prevent or limit public exposure in the ingestion

pathway:12

Preventive protective actions are those taken by farmers to prevent contamination of

milk, water and food products (e.g., sheltering dairy animals and placing them on stored

feed and covered water).

Emergency protective actions are those taken by public officials to address contaminated

milk, water and food products, and divert such products from animal and human

consumption (i.e., embargoes).

Loss Estimates

Indirect costs due to a nuclear event would almost certainly exceed those of clean-up. These

would include costs attributable to the stigma associated with radiation and radioactive material

in the mind of the public. Because of this stigma, the social and political impacts of a nuclear

event may greatly exceed any justifiable limits. There have been instances where the public has

avoided radiologically contaminated areas and shunned affected businesses and their products

long after any credible health threat has been eliminated.

12 http://www.hsem.state.mn.us/uploadedfile/dir_hand/EMDH_C- 13_RadiologicalEmergencyPreparednessProgram.pdf

Northeastern Idaho


54

Hazard Evaluation

The frequency of nuclear accidents is extremely low, the last reported nuclear accident at the

INL was in 1979. There were no impacts to the general public during that event. There was a

reactor accident at the INL in the early sixties that claimed the lives of three individuals. All of

the Counties in the Region except Madison and Teton lie within the INL‟s ingestion pathway.

Planning for ingestion related releases should be considered in the entire Region because of the

fear that will be associated by the general public regarding a release of radioactive materials

from the INL. The ingestion pathway for the Reactor Technology Center at the INL covers a

radius of 69 miles.

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

Fremont

Madison

Teton

Clark

Butte

Bonneville

Clark

Jefferson

Lemhi

(Medium) 2

(High) 3

Figure 2.28 Nuclear Risk Ranking

Northeastern Idaho


55

Hazardous Material Event

Description

Substances that, because of their chemical or physical characteristics, are hazardous to humans

and living organisms, property, and the environment, are regulated by the U.S. Environmental

Protection Agency (EPA) and, when transported in commerce, by the U.S. Department of

Transportation (DOT). EPA regulations address “hazardous substances” and “extremely

hazardous substances”.

EPA chooses to specifically list hazardous substances and extremely hazardous substances rather

than providing objective definitions. Hazardous substances, as listed, are generally materials

that, if released into the environment, tend to persist for long periods and pose long-term health

hazards for living organisms. They are primarily chronic, rather than acute health hazards.

Regulations require that spills of these materials into the environment in amounts at or above

their individual “reportable quantities” must be reported to the EPA. Extremely hazardous

substances, on the other hand, while also generally toxic materials, are acute health hazards that,

when released, are immediately dangerous to the life of humans and animals as well as causing

serious damage to the environment. There are currently 355 specifically listed extremely

hazardous substances listed along with their individual “threshold planning quantities” (TPQ).

When facilities have these materials in quantities at or above the TPQ, they must submit “Tier

II” information to appropriate state and/or local agencies to facilitate emergency planning.

DOT regulations provide the following definition for the term “hazardous material”:

Hazardous material means a substance or material that the Secretary of Transportation has

determined is capable of posing an unreasonable risk to health, safety, and property when

transported in commerce, and has designated as hazardous under section 5103 of Federal

hazardous materials transportation law (49 U.S.C. 5103). The term includes hazardous

substances, hazardous wastes, marine pollutants, elevated temperature materials, materials

designated as hazardous in the Hazardous Materials Table (see 49 CFR 172.101), and

materials that meet the defining criteria for hazard classes and divisions in part 173 of

subchapter C of this chapter.

When a substance meets the DOT definition of a hazardous material, it must be transported

under safety regulations providing for appropriate packaging, communication of hazards, and

proper shipping controls.

In addition to EPA and DOT regulations, the National Fire Protection Association (NFPA)

develops codes and standards for the safe storage and use of hazardous materials. These codes

and standards are generally adopted locally and include the use of the NFPA 704 standard for

communication of chemical hazards in terms of health, fire, instability (previously called

“reactivity”), and other special hazards (such as water reactivity and oxidizer characteristics).

Diamond-shaped NFPA 704 signs ranking the health, fire and instability hazards on a numerical

scale from zero (least) to four (greatest) along with any special hazards, are usually required to

be posted on chemical storage buildings, tanks, and other facilities. Similar NFPA 704 labels

may also be required on individual containers stored and/or used inside facilities.

Northeastern Idaho


56

While somewhat differently defined by the above organizations, the term “hazardous material”

may be generally understood to encompass substances that have the capability to harm humans

and other living organisms, property, and/or the environment. There is also no universally

accepted, objective definition of the term “hazardous material event.” A useful working

definition, however, might be framed as: Any actual or threatened uncontrolled release of a

hazardous material, its hazardous reaction products, or the energy released by its reactions that

poses a significant risk to human life and health, property and/or the environment.

The Tables that follow shows the Tier II facilities along with their Protective Action Distances

(PAD). These PADs are based on a hypothetical worst-case scenario where the total quantity of

the material explodes or is released directly into the air. Hazardous materials are also very

commonly stocked and used by businesses in smaller quantities than those required to submit

Tier II reports, as well as by private individuals. Thus, it is reasonably safe to consider the entire

Region and its inhabitants to be exposed to risk from hazardous materials. In spite of their

widespread use, however, hazardous material events are relatively rare and even more rarely

cause death, injury or large-scale property damage. Figure 2.29 illustrates the location of the

PADs in the Region.

Facility Address City/Zip Product PAD (feet)

Antelope

Substation

6 miles east of Hwy Junction

20 & 26 Arco, 83213 Sulfuric Acid 150

Butte County

Department of

Noxious Weeds

159 N. Idaho Street Suite #105

Arco, 93213 Assert 150

ITD 2005-10B-

ARCO 2795 US 20-26 Arco, 83213 Unleaded Gasoline 2640

V-1 Propane 540 Grand Avenue Arco, 83213 Propane 5280

Howe Farms Hwy 22 Howe, 83224 Diesel fuel 2640

Table 2.10 Butte County Tier II Facilities with PAD

Facility Address Product PAD (feet)

Busch Agricultural Resources, Inc.

5755 S. Yellowstone Hwy.

Chlorine 24,288

City of Idaho Falls Wastewater

Treatment Plant

4055 Glen Koester Lane

Chlorine 24,288

Falls Fertilizer, Inc. 1157 Lindsay Blvd. Aluminum Phosphide 8,967

Idaho Barley Elevator at Osgood

2121 W. 145 N. Aluminum Phosphide 8,967

Penford Products Co.

1088 W. Sunnyside Road

Phosphorus Oxychloride 7,392

Quadra Chemicals Inc.

5200 North 15th

East Chlorine 24,288

Simplot Grower Solutions

3192 East 49th

North Aluminum Phosphide

(Fumitoxin , Weevelcide)

8,967

UAP Distribution Inc.

3030 E. 49TH N.

Zinc Phosphide

8,967

Table 2.9 Bonneville County Tier II Locations of PAD > 1 Mile

Northeastern Idaho


57


Amps Substation

20 miles West of

Dubois Dubois, 83423 Sulfuric Acid 150

ITD 2005-5C-

Dubois 170 S. Idaho St Dubois, 83423

Diesel Fuel,

Unleaded Gasoline 2,640

RDO Processing,

LLC (formerly

Blaine Larsen

Farms) 72 Dehigh Road Dubois, 83423 Propane 5,280

Wagoner Oil

Company Reynolds Street Dubois, 83423

Diesel Fuel #1,

Diesel Fuel #2,

Unleaded Gasoline 2,640

Table 2.11 Clark County Tier II Locations


Challis Stinker

Station 88 Highway 93 South Challis, 83226 Diesel Fuel 2,640

ITD 2005-7c-

Challis US 93 Challis, 83226 Diesel Fuel 5,280

Salmon River

Propane

1257 E. Valley

Street Challis, 83226 Liquefied Petroleum Gas 5,280

Thompson Creek

Mine PO Box 62

Clayton,

83227

Liquid Hydrocarbon (Diesel

Fuel) 5,280

ITD 2005-7c-

Mackay 62101 US 93

Mackay,

83251 Diesel Fuel 2,640

Idaho

Transportation

Department Dist. 4

Mile Post 127.85

E/B, State

Highway 21 Stanley, 83278 Gasoline 2,640

Table 2.13 Custer County Tier II Locations

Facility Address City/Zip Product PAD

Ashton Elementary 168 South 1st St Ashton, 83420 Liquefied Petroleum Gas 5,280

Fall River Rural

Electric

1150 North 3400

East

Ashton, 83420 Liquefied Petroleum Gas 5,280

North Fremont High

School

3581 East 1300

North

Ashton, 83420 Liquefied Petroleum Gas 5,280

Powerline

Construction

3459 Hwy 20 Ashton, 83420 Blasting Caps, TNT 5,280

Simplot Grower

Solutions

751 North 3900 East Ashton, 83420 Aluminum Phosphide, Carbofuran,

Diazinon, EPTC, Methamidophos,

Triallate

8,967

Valley Wide Travel

Plaza

921 North Hwy 20 Ashton, 83420 Diesel, Gasoline, Liquefied

Petroleum Gas

5,280

Walters Produce 8510 E Hwy 33 Newdale, 83436 Liquefied Petroleum Gas 5,280

Amerigas Propane

L.P.

835 South

Yellowstone

St Anthony, 83445 Liquefied Petroleum Gas 5,280

Northeastern Idaho


58

Facility Address City/Zip Product PAD

Simplot Grower

Solutions

2555 South

Yellowstone

St. Anthony, 83445 Aldicarb, Aluminum Phosphide,

Ammonia Anhydrous, Carbofuran,

Metam Sodium, Mocap, O-

Dimethyl S- Phosphorodithioate,

Phorate, Phosphonic Acid,

Potassium N-

Methyldithiocarbamate, S-Ethyl

Dipropylthiocarbamate, Telone II

Soil Fumigant, Triallate, Vydate,

Dimethoate, Eptam 7e, K-Pam Hl,

Phorate, Thimet, Temik, Weevil-

Cide, Vydate Clv

8,967

Table 2.14 Fremont County Tier II Locations


Big Grassy Substation

3 miles north

and 1.25

miles east of

Camas

Camas, 83425 Sulfuric Acid

150

Idaho Fresh Pak, Inc.

(Lewisville Plant)

529 North

3500 East Lewisville, 83431

SSB 567

LCC-582F

Sulphamic Acid

Isopropyl Alcohol

Anhydrous

CUT 414

Wasa-A -Chlor

Foam-a-chlor

Draw (see note)*

KEY 547

QCPD 655

Steammate EM760

1000

ITD 2005-1J-MUD

LAKE 973 E 1500 N Mud Lake, 83450

Diesel Fuel

Asphalt

Cements

1000

Dyno Nobel, Inc

N2, NE4,

NW4, Section

24, TWP4,

TWP4 N RG

E 37

Rigby, 83442 Ammonium Nitrate

High Explosive

5280

ITD 2005-1J-RIGBY

206 North

Yellowstone

Rigby, 83442

DIESEL FUEL

UNLEADED GASOLINE

ASPHALT CEMENTS

2640

Maverik Country Store

#152

200 East

Main Rigby, 83442 Gasoline 2640

Potato Products of

Idaho, LLC

398 North

Yellowstone

Highway

Rigby, 83442 Anhydrous Ammonia 7392

Northeastern Idaho


59


Qwest Corporation -

Rigby Central Office

(370370)

126 North

State Rigby, 83442 Sulfuric Acid 150

Rigby Substation

610 North

Annis

Highway

Rigby, 83442 Sulfuric Acid 150

Maverik Country Store

#156

90 West Hwy

26 Ririe, 83443 Gasoline 2640

Jefferson Substation

4 miles West

of Interstate

15 Roberts

Exit

Roberts, 83444 Sulfuric Acid 150

Western Farm Service,

Inc. - Roberts

272 North

Bassett Rd.

Roberts, 83444

Ammonia, Anhydrous

Diesel Fuel

Gasoline

Metam Sodium (ENVIRONMENTALLY HAZARDOUS SUBSTANCES, LIQUID, N.O.S.)

Propane

Sulfuric Acid

Phosphoric Acid

EPTC (HERBICIDE)

Aldicarb

OXAMYL (PESTICIDE)

Endosulfan

Fludioxonil

Mancozeb

7292

Table 2.15 Jefferson County Tier II Locations


Idaho Power Co.-Pahsimeroi

Fish Hatchery 22 Hatchery Loop Ellis, 83235 Formaldehyde 150

ITD 2005-2l-Gibbonsville Us 93

Gibbonsville,

83463 Diesel Fuel 2640

ITD 2005-2l-Leadore Sh 28 Leadore, 83464 Diesel Fuel 2640

93 Mini-Market 517 Challis Salmon, 83467 Gasoline 2640

Beartrack Mine

Forest Road #242

Leesburg Salmon, 83467

Aluminum Hydroxychloride

40%-70% 5280

Centurytel - Salmon CO 111 South Terrace Salmon, 83467 Sulfuric Acid 150

Idaho Power Company -

Salmon 800 N. St. Charles Salmon, 83467 Diesel Fuel 2640

ITD 2005-2l-Salmon 1015 Hwy 93 N Salmon, 83467 Unleaded Gasoline 2640

John C Berry & Sons, Inc 402 N St Charles Salmon, 83467 Gasoline 2640

Northeastern Idaho


60


John C Berry & Sons, Inc/

Dba Main Street Chevron 700 Main Salmon, 83467 Diesel Fuel 2640

Table 2.16 Lemhi County Tier II Locations


Basic American

Foods 40 East 7

th North Rexburg, 83440 Chlorine 24,288

Valleywide Coop

2003 South

Yellowstone

Highway

Rexburg 83440 Aluminum Phoshpide 8,967

Valleywide Coop 520 E. Moody

Hwy Rexburg, 83440 Aluminum Phosphide 8‟967

NorSun Food

Group, Inc 903 E. 3000 North Sugar City, 83448

Anydrous Ammonia

7,392

Table 2.17 Madison County Tier II Locations


ITD 205-1T-

Driggs 157 N SH33 83422

Diesel Fuel

Unleaded Gasoline

2640

V-1 Propane 250 S. Highway 33 83422

Propane

5280

John C Berry &

Sons, Inc. 104 Leigh 83452

Diesel Fuel

Gasoline

2640

Table 2.18 Teton County Tier II Locations

Northeastern Idaho


61

Figure 2.29 Tier II PADs

Northeastern Idaho


62

Impacts

Because hazardous materials are so widely used, stored and transported, a hazardous material

event could take place almost anywhere. Further, many hazardous materials are used, stored and

transported in very large quantities so that the impacts of an event may be widespread and

powerful. Regulations and safety practices make such large scale events unlikely, but smaller

scale incidents may have severe impacts including:

Human deaths, injuries, and permanent disabilities

Livestock/animal deaths

Destruction of vegetation and crops

Property damage and destruction

Pollution of groundwater, drinking water supplies, and the environment

Contamination of foodstuffs, property, land and structures

Temporary or long-term closure of transportation routes and/or facilities

Loss of business and industrial productivity

Utility outages

Clean-up and restoration costs

Losses and inconvenience due to evacuation

Loss of valuable chemical product

Loss Estimates

Hazardous Material losses occur primarily due to the displacement of populations and the

interruption of business. The Region has several facilities that use hazardous materials. These

facilities are located in close proximity to major population centers in the Counties. A release of

hazardous materials in this area could potentially require the evacuation of the neighborhoods

located in the vicinity of these facilities.

Hazard Evaluation

Hazardous Materials are widely used, stored, and transported in the Region. The largest PAD in

the Region is in Madison County and is associated with the chlorine storage facility at Basic

American Foods. The PAD for this hazard covers the entire City of Rexburg and much of the

surrounding area.

The transportation of hazardous materials is also a concern throughout the Region. Hazardous

Materials can be expected to be transported on all major roadways in the Region however,

special concern is placed on I-15, Highway 20, Highway 26, Highway 93. Eastern Idaho and

Union Pacific Railways also carry significant quantities of hazardous materials.

Northeastern Idaho


63

Magnitude

(Low)

1

(Medium)

2

(High)

3

Fre

qu

ency

(Low) 1

(Medium) 2

(High) 3 Bonneville

Teton

Clark

Butte

Custer

Fremont

Jefferson

Lemhi

Madison

Figure 2.30 Hazard Materials Risk Ranking

Northeastern Idaho


64

Section 3 Mitigation Projects

Hazard mitigation is defined as any cost-effective action(s) that has the effect of reducing,

limiting, or preventing vulnerability of people, culture, property, and the environment to

potentially damaging, harmful, or costly hazards. Hazard mitigation measures which can be used

to eliminate or minimize the risk to life, culture and property, fall into three categories:

1) Those that keep the hazard away from people, property, and structures,

2) Those that keep people, property, or structures away from the hazard, and

3) Those that reduce the impact of the hazard on victims, i.e., insurance.

This mitigation plan identifies key strategies that fall into all three categories.

Hazard mitigation measures must be practical, cost effective, and culturally, environmentally,

and politically acceptable. Actions taken to limit the vulnerability of society to hazards must not

in themselves be more costly than the anticipated damages.

The primary focus of this Plan is on decision making for land use and capital investment.

Mitigation proposals are made and prioritized based on risk assessment that takes into account

the magnitude of hazards, their frequency of occurrence, and the vulnerabilities of the

community to them. This helps to assure that risk reduction efforts, whether for homes, roads,

public utilities, pipelines, power plants, public works, or other projects, are both necessary and

cost effective.

In the past, hazard mitigation has been one of the most neglected emergency management

programs. Because disaster events are generally infrequent and the nature and magnitude of the

threat is often ignored or poorly understood priority to fund and implement mitigation measures

is low. Mitigation success can be achieved, however, if accurate information is portrayed to

decision makers and the public through complete hazard identification and impact studies,

followed by effective mitigation management.

Prioritization Process

Prioritization of the Mitigation Projects in the individual Counties occurred at the Local

Mitigation Workshop where representatives from the Counties and the participating Cities came

together to approve the risks severity ranking, the goals, and associated projects. The projects

were selected based on the goals and related objectives of the respective county‟s Plan. The

basic tenants of the process, as discussed in the scope and mission statement of this Plan, was life

safety first, protection of critical infrastructure second, and reduction of repetitive loss third.

Those projects that were selected and listed and then roadmapped as the four highest priority

projects were selected based on the following criteria:

Hazard Magnitude/Frequency

Potential for repetitive loss reduction

Benefit / Cost

Vulnerability to the Community

Population Benefit

Property Benefit

Northeastern Idaho


65

Economic Benefit

Project Feasibility (environmentally, politically, socially)

Potential project effectiveness and sustainability

Potential to mitigate hazards to future development

Each county selected the four priority projects based on the input from the workshop. The

Commissioners reviewed the projects and approved the ranking.

Those priority projects which have been deemed to cross county are:




Mackay Dam Failure Notification System Project




Upper Snake River Basin Cloud Seeding (in Progress)

Descriptions of the individual projects are found in Attachment 1

Additional Projects which might be considered include:

Ingestion Pathway Planning with INL

Drought Planning

Winter Storm Road Closure and Sheltering

Living Wind Breaks

Regional “reverse” Emergency Notification System

Single Loop Power Supplies in Teton and Lemhi County

Flood Protection Projects between Madison and Jefferson Counties

Fuel Reduction Projects on County Borders

Regional Hazardous Materials Commodity Flow Study

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66

This

Page

Intentionally

Blank

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67

Attachment 1

Multi-County Mitigation Projects

Northeastern Idaho


68

This

Page

Intentionally

Blank

Northeastern Idaho


69


1. Install Surveillance System

2. Conduct a LIDAR fly over of the entire County paying specific interest to Idaho Falls and

Ammon to determine topography and building heights

3. Develop a “Vertical” Evacuation/Sheltering Plan

Purpose and Need

A catastrophic failure of the Ririe Dam would be devastating to the Cities of Idaho Falls and

Ammon. In 2007, using BHS SHSP Planning Funds, Bonneville County conducted a project to

develop an evacuation plan for a catastrophic failure of the Ririe Dam. The study and resulting

planning effort clearly demonstrated that there is no reasonable solution to evacuation of the

inundation zones within the required time. One of the key issues raised by the study was the need

to begin evacuation almost immediately and even then it is physically impossible to relocate the

total population. The Ririe Dam is unmanned, and as such, the capability of early notification

does not exist thus exacerbating the problem even further. There is a need therefore to conduct

three related projects, referenced above all, which are required to protect the citizens of

Bonneville County from the life threatening effects from a Ririe Dam Failure.

Project Description

As stated previously, the capability to notify citizens of a Ririe Dam failure requires some sort of

surveillance of the Dam Structure. The installation of a Surveillance or Early Warning System

(EWS) is required because the dam is not manned. The elements of a surveillance or early

warning system are as follows:

(1) A method for detecting flood events.

(2) A decision-making process.

(3) A means of communicating warnings between operating personnel and local public safety

officials.

(4) A means for local public safety officials to effectively communicate the warnings to the

public and carry out a successful evacuation of the threatened area.

All of these components must be in place to have a successful surveillance or EWS. An effective

evacuation requires that public safety officials downstream of the dam be notified by the dam

owner of specific areas to be evacuated. The public warning and evacuation process is the role

of the emergency response officials located downstream of the dam.13

Although ensuring public safety in the event of dam failure is the goal of this program, a

surveillance or EWS must be designed to provide warning as needed during large operational

discharges as well. Like hydrological induced dam failures, where a life-threatening discharge

occurs, controlled large scale discharges can have similar effects. By integrating the surveillance

and warning systems together the public can be assured that the information is correct and

credible. The system is legitimized each time it is used thus focusing the public‟s attention to the

provided warnings. The development of decision criteria must be also integrated into both the

13 http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf

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notification for potential frequent flood events as well as rare extreme flood events, which may

pose a threat to the safety of the dam.14

The range of hardware includes reservoir elevation monitoring systems to full basin rainfall

monitoring systems with real-time rainfall-runoff modeling. The types of data communication

systems in use include manual observation by a dam tender, GOES satellite telemetry,

UHF/VHF polling radio systems, and ALERT format radio systems. Other ideas that may be

added to the system include downstream flow monitors, webcam examination of the dam and

river flows, and reservoir level indicators.

A second and critical component of the protection system is an Evacuation Plan. As stated

above, even with the implementation of a surveillance or EWS an evacuation plan where the

total population is relocated is not possible. The proposed alternative to the total evacuation is

some sort of “vertical” evacuation or sheltering. To conduct this type of activity the impacted

areas must be evaluated topographically to determine areas that must be evacuated, based on

depth and areas where relocation within the inundation zone may take place. To accomplish this

planning effort a LIDAR based topography model must be developed. LIDAR provides

elevation accuracies within centimeters. This data will allow hydrologists and emergency

planners to work together to develop a vertical evacuation/sheltering plan.

Cost Estimate

The rough order of magnitude cost estimate for this project is $300,000. (Includes Evacuation

Planning)

Benefit Cost Analysis (BCA)

Cost Benefit Analysis is not necessary for this project if funding is provided by the Bureau of

Reclamation.

Funding Options

This project should be funded with a combination of SHSP Funds and Funding from the Bureau

of Reclamation. This project does not qualify for the Pre-Disaster Mitigation Grant Program.

14 http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf

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1. Install Surveillance System

2. Develop an Evacuation Plan

Purpose and Need

A catastrophic failure of the Palisades Dam would be devastating to Bonneville, Madison, and

Jefferson Counties. With any catastrophic dam failure, protective actions require evacuation to

populations downstream of the Dam. The Palisades Dam is manned from 8 am to 5 pm Monday

through Friday and unmanned the rest of the time, and as such, the capability of early

notification does not exist during unmanned hours. There is a need therefore to conduct two

related projects, all of which are required to protect the citizens of Bonneville, Madison, and

Jefferson Counties from the life threatening effects of a Palisades Dam Failure.

Project Description

The capability to notify citizens of a Palisades Dam failure requires some sort of surveillance of

the Dam Structure. The installation of a surveillance or Early Warning System (EWS) is

required because of the unmanned times. The elements of a surveillance or early warning system

are as follows:




officials.


public and carry out a successful evacuation of the threatened area.

All of these components must be in place to have a successful surveillance or EWS. An effective

evacuation requires that public safety officials downstream of the dam be notified by the dam

owner of specific areas to be evacuated. The public warning and evacuation process is the role

of the emergency response officials located downstream of the dam.15

Although ensuring public safety in the event of dam failure is the goal of this program, a

surveillance or EWS must be designed to provide warning as needed during large operational

discharges as well. Like hydrological induced dam failures, where a life-threatening discharge

occurs, controlled large scale discharges can have similar effects. By integrating the surveillance

and warning systems together the public can be assured that the information is correct and

credible. The system is legitimized each time it is used thus focusing the public‟s attention to the

provided warnings. The development of decision criteria must be also integrated into both the

notification for potential frequent flood events as well as rare extreme flood events, which may

pose a threat to the safety of the dam.16

The range of hardware includes reservoir elevation monitoring systems, to full basin rainfall



15 http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf 16 http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf

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72




A second and critical component of the protection system is an Evacuation Plan that can be

developed and implemented by all three Counties.

Cost Estimate

The rough order of magnitude cost estimate for this project is $350,000. (Includes Evacuation

Planning)


Cost Benefit Analysis is not necessary for this project if funding is provided by the Bureau of

Reclamation.

Funding Options

This project should be funded with a combination of SHSP Funds and Funding from the Bureau

of Reclamation. This project does not qualify for the Pre-Disaster Mitigation Grant Program.

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Install a Dam Failure Warning System on the Island Park Reservoir Dam

Purpose & Need

The Island Park Reservoir Dam is owned by the US Bureau of Reclamation. It is upstream of

the Last Chance area in Island Park City by approximately 3 miles. A catastrophic failure of the

dam would not allow sufficient time to evacuate downstream populations in Last Chance without

rapid notification. The dam is unmanned and not monitored for catastrophic failure.

Project Description

The County seeks to develop an Early Warning System (EWS) and link it to a rapid notification

system operated out of the County Dispatch Center. The following are suggested Dam Failure

Warning System Components:




officials.


public and carry out a successful evacuation of the threatened PAR.

All of these components must be in place to have a successful EWS. An effective evacuation

requires that public safety officials downstream of the dam be notified by the dam owner of

specific areas to be evacuated. The public warning and evacuation process is the role of the

emergency response officials located downstream of the dam 17

Although ensuring public safety in the event of dam failure is the goal of this program, an EWS

must be designed to provide warning as needed during large operational discharges as well.

Most hydrological induced dam failures will involve life-threatening discharges early in the

event. If the EWS is not used on a regular basis for floods, it will most likely not function

effectively when needed for a major overtopping event which may cause a dam failure. The

development of decision criteria must take into account both the notification for potential

frequent flood events as well as rare extreme flood events, which may pose a threat to the safety

of the dam.18







Cost Estimate

The rough order of magnitude cost estimate for this project is $250,000.

17

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http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf

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The BCA will be conducted as part of the engineering design for this project.

Funding Option

Suggested funding options include a combination of Bureau of Reclamation and/or Pre-Disaster

Mitigation Grant funding

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Mackay Dam Failure Notification System Project Description

Install a Dam Failure Warning System on the Mackay Reservoir Dam

Purpose & Need

The Mackay Dam is owned by the Lost River Irrigation District. It is upstream of the City of

Mackay by approximately 4 miles. A catastrophic failure of the dam would not allow sufficient

time to evacuate downstream populations in Mackay. The dam is unmanned however, there is

an electronic level indicator that is monitored daily that might be the beginning of an electronic

warning system.

Project Description

The following are suggested Dam Failure Warning System Components:




officials.


public and carry out a successful evacuation of the threatened PAR.

All of these components must be in place to have a successful EWS. An effective evacuation

requires that public safety officials downstream of the dam be notified by the dam owner of

specific areas to be evacuated. The public warning and evacuation process is the role of the

emergency response officials located downstream of the dam 19

Although ensuring public safety in the event of dam failure is the goal of this program, an EWS

must be designed to provide warning as needed during large operational discharges as well.

Most hydrological induced dam failures will involve life-threatening discharges early in the

event. If the EWS is not used on a regular basis for floods, it will most likely not function

effectively when needed for a major overtopping event which may cause a dam failure. The

development of decision criteria must take into account both the notification for potential

frequent flood events as well as rare extreme flood events, which may pose a threat to the safety

of the dam.20







Cost Estimate


19

http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf 20

http://www.usbr.gov/pmts/infrastructure/inspection/waterbulletin/195mar2001.pdf

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Cost Benefit Analysis is not necessary for this project as funding would have to come through

the Lost River Irrigation District.

Funding Option

Suggested funding options include a combination of local irrigation company funds, NRCS

funding, and Pre-Disaster Mitigation Grant funding.

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Identify vulnerable power poles on the INL lands and find ways to protect them.

Purpose and Need

Butte County‟s electrical power supply comes from the Goshen Substation in Bingham County.

The power line crosses the Idaho National Laboratory (INL) enroute to Butte County. The area

is susceptible to damaging wildfires and the County, and neighboring Custer County, has lost

power several times because of damage to power poles. This transmission line is the only power

supply to both counties.

Project Description

Working with the INL and Bonneville County, the County will develop an agreement to protect

the Power Transmission System to Butte County. The project should include protection of the

power poles from Wildfire by either replacing the wooden poles with metal poles or by clearing

vegetation from around the poles in such a manner that they are not at risk. This methodology

would require constant maintenance and surveillance.

Figure 3.1 Major Transmission Lines

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Cost Estimate



Cost Benefit Analysis will be conducted for this project, see line 36 of roadmap.

Funding Options

Funding for this project should come from a combination of funds for the INL, a Pre-Disaster

Mitigation Grant, and Idaho Power.

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Re-Channel the South Fork of the Snake River between the Rail Road Bridge and the Twin

Bridges at Archer.

Rip Rap the north banks of the north channel of the Snake River upstream of the north Twin

Bridge at Archer.

Rebuild the Lenroot Canal Diversion Dam.

Purpose and Need

In 1997 a Disaster was declared for several counties in southeastern Idaho due to high run off

from the snow pack. The South Fork of the Snake River was one of the rivers included in that

Declaration. Several post-disaster projects were conducted after the flooding event including

repair of the Twin Bridges on the Archer Highway. One of the issues unnoticed at the time was

the creation of a gravel bar below the Rail Road Bridge and above the Twin Bridges at Archer.

The gravel bar changed the historic flow at the location of the River. The main flow of water

took a southern channel with a limited amount taking a northern channel.

After the flood of 1997 the south channel at this location was virtually blocked by the gravel bar

so that all the flow during normal periods went to the northern channel. This flow has damaged

stream banks through erosion, including the bank adjacent to the support structures for the most

northern of the Twin Bridges at Archer. The Lenroot Canal diversion is washed out during high

flows because of the increased capacity in the North Channel. Other issues include the loss of

use of southern channel boat docks at the County/BLM parks.

One serious concern, voiced by the canal company, is the tendency of the River to seek a

southern channel naturally. Since 1997 the River has began to cut a new channel across the

Island located in the River below the Twin Bridges. If this cut grows, and with the main flow of

the River which is mostly to the south at this location, there is a significant possibility that the

Lenroot Canal would lose its water supply leaving 3000 acres of land without irrigation.

Project Description

The Lenroot Canal Company has suggested that the Channel be returned to pre-1997 conditions

by placing a diversion at the entrance to the old southern (now dry) channel. This channel was

previously rip rapped and protected as required for the high flows experienced on the river.

Other issues needing attention is the rip rapping of the northern banks of the North Channel that

are now seriously eroding. This erosion is threatening the northern supports of the north Twin

Bridge on the Archer Highway. The Canal Company has met with several local, State, and

Federal Agencies over the past several years to get this project underway, but to no avail. This

project seeks to pull together all players to resolve the issue for the best good of the irrigators,

the environment, the fish and wildlife, and the recreational users. An additional project, once the

flows are better regulated would be to rebuild the Lenroot Canal diversion dam to pre-1997

conditions. The chart below illustrates the concerns and project need.

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Figure 9.1.2 Archer Highway Bridge Project

Cost Estimate

The rough order of magnitude cost estimate for the entire project is $850,000.


A BCA will be necessary for those parts of the project that request Federal Funding. The BCAs

should be done for the entire project and then conducted for individual tasks as provided for in

the funding requirements.

Funding Options

This project should be funded by a combination of private funds, Pre or Post Disaster Mitigation

Grants, or by the sale of the gravel that needs to be removed from the channel. The sale of the

gravel would require participation by the Idaho Department of Lands, but it is estimated by the

Canal Company that the gravel sale would more than finance the entire project need.

Cut from North to South Channels Beginning to Form.

Boat Dock High and Dry

During Normal Flows

South Channel Dry

During Normal Flows

Existing Rip Rap

Previous Bank Maintenance Project

Problem: North Bridge on Archer Highway

Bank Erosion—Undermining of Bridge Abutment

Significant New Bank Erosion

Due to Channel Change

Old Main Channel Now Dry!

Massive Gravel Bar

Formed as Part of 1997 Flood

General Location of Proposed Solution:

Rock Diversion

Lenrood Canal Diversion

Lenrood Canal Head

Lenrood Canal Provides

Irrigation Water to 3000 Acres —

Crops Totaling $5,000,000 Annually

Archer Highway Bridge Project

Re-channel of Snake River to Previous

1997 Channel Flows

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Develop hazardous materials transportation frequency documentation.

Purpose and Need

An increase in hazardous material traffic needs to be documented on Highway 20 and I-15

throughout the Region. Tier II facilities are well documented, but documentation needs to be

prepared for future mitigation and response deeds to hazardous transportation events. The

objective of the project is to protect citizens from the release of hazardous materials in

transportation.

Project Description

Conduct a hazardous materials flow study for Highway 20, I-15, and the railroad line running

through the Region.

Cost Estimate



A BCA is not required for this project.

Funding Options

Apply for an HMEP Grant

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Upper Snake River Basin Cloud Seeding

In Progress

The water resources of the Snake River Basin (both surface and ground) are being stressed by

drought, population growth, and increasing demands by agriculture, cities, and recreational

activities. Therefore, the High Country Resource Conservation and Development Council

conducted a winter cloud seeding program to augment snow packs. The target areas were Upper

Snake River Basin and those watersheds draining into Water Basin 31. The program ran from

November 1, 2007 to April 1, 2008 and was contracted out to Clark County and Let it Snow Inc.

Cloud Seeding Donations for winter 07-08:

A&B Irrigation District City of St. Anthony Mud Lake SWCD

Bannock County East Cassia SWCD New Sweden Irrigation District

Bingham County East Side SWCD North Bingham SCD

Bingham Ground Water District Fremont County North Fremont Canal Systems, Inc.

Bonneville County Fremont County Snowmobile Club Place Farms Ltd.

Central Bingham SWCD Fremont-Madison Irrigation District Power County

City of Ammon Idaho Dept. of Water Resources Progressive Irrigation District

City of Rexburg Idaho Falls Power Teton Count

City of Sugar City Idaho Irrigation District Teton Irrigation & Manufacture Co.

Clark County Jefferson County Water District #32-C

Clark SCD Madison County Water District 1

Clark-Jeff. Ground Water District Madison SWCD West Side SWCD

Results of Snake River Basin Cloud Seeding 07-08:

IDWR perspective on weather modification said there is conceptually defensible and

documented success. It is difficult to quantify the effectiveness because so many variables exist.

Success of the program relies on the quality of the program as well as its operators. Current

SNOTEL data shows reported areas have experienced more than 100 percent precipitation during

this winter season. With many storms moving though the state, it was a good year to activate the

weather modification project.

The North American Weather Consultants, Inc. prepared results from regression equations

developed for the operational upper Snake River cloud seeding program. The results showed the

northern region ranged from 0.29 to 0.93 inches of additional water content. While the eastern

region ranged from 0.29 to 0.44 inches of additional water content.

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Future Goals for the Snake River Basin Cloud Seeding:

$150,000 to be raised for next year's cloud seeding

project

Partnership with State of Idaho

Repair generators

Hire intern to help with fundraising

more SNOTEL research sites

What is cloud seeding?

Cloud seeding is a proven tool to increase precipitation and numerous evaluations have indicated

that cloud seeding , when properly applied, can produce precipitation increases up to 10% or

greater. Cloud seeding is a form of weather modification. It can be used to disperse fog,

suppress hail, or control winds, but is most often used to increase precipitation. It introduces

other particles into a cloud to serve as cloud condensation nuclei and aid in the formation of

precipitation. 21

21 http://www.hcountryrcd.org/cloud%20seeding.htm

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